The Science of Football: The Math, Technology, and Data Behind America's Game

By Will Carroll, Tyler Brooke and Peter King

In The Science of Football, sportswriter and injury expert Will Carroll teams up with writer and podcast host Tyler Brooke to show how understanding the science behind American football helps fans appreciate the sport even more. The authors cover topics like injuries, equipment, and analytics from all sides of the game, including offense, defense, and special teams.

After reading this fascinating addition to the successful Science of series, football enthusiasts at the professional, college, and high school levels and science geeks alike will better appreciate the game--no matter which teams are playing!

• Language: English
• Publisher: Sports Publishing
• Release date: Sep 6, 2022
• ISBN: 9781683584605

Book preview

INTRODUCTION

Smashmouth. Slobberknocker. Hog Mollies. Big Uglies. There’s a ton of fun football terms that sound like exactly what they are. To the uninitiated, NFL-style American football—which we will henceforth just call football for ease, with apologies to the world game we’ll call soccer here—is anything but scientific. It’s big men smashing into other big men. George Plimpton once called football violence punctuated by committee meetings. He wasn’t wrong, but the game has evolved from a more violent and frankly more American game, into something that looks more like America in 2022. There’s more technology, more complexity, and much, much more science in the game.

What we have tried to present here is the idea that the principles of science are woven into the fabric of the game in a way that is either invisible or taken for granted to such a degree that the science is ignored. Newton showed us that force is equal to mass times acceleration, but few of us do that equation when an edge rusher beats his man and bashes the quarterback, causing the ball to flutter out of his hands while his spine tries to deal with an unexpected trauma.

Football is not a game that innovates quickly. Ten years ago, the Super Bowl came to our town of Indianapolis and that game—Eli Manning’s Giants over Tom Brady’s Pats—was best known for the helmet catch. I recently watched highlights of that game and it looks almost exactly like football does in 2022. Things have changed, to be sure, but those things are often not apparent to the most casual watchers . . . like the ones who show up once a year to watch the Super Bowl, or at least the commercials.

If we take it back to 2002’s Super Bowl, we’re met with the St. Louis Rams of Kurt Warner and—oh my—Tom Brady’s Patriots. That Greatest Show on Turf game was one of the legend makers for Brady and his brief flirtation with retirement reminds us that his career is an absolute outlier. When George W. Bush’s dad flipped the coin at that Super Bowl, the season after 9/11, the US was in its first months of the War on Terror in Afghanistan and it hadn’t yet reached Iraq.

Still, the game looked modern. There was more running, less passing, but it’s not a far cry from what we see today. A land war in Asia came and went, while football just adjusted, a little bit and a little bit more, year after year. The game evolved towards a quarterback-dominated affair, forcing small adjustments to defenses, which led to more changes in offenses.

Helmets? Shoulder pads? Stadiums? All pretty much the same, then and today.

But just under the surface, there have been plenty of changes. The players have, as always, continued to get bigger, faster, and stronger. They’ve also gotten smarter, taken more control of their careers and their voices. From the broadcast you watch to the app you make a bet on, from the offense to the defense to the front office, the game of football is reliant on innovation, data, and even math for many of its innovations.

Material science? That’d be the lightweight shoes, the turf they play on, or the kevlar used in so many repaired joints.

Satellites and GPS? Yep, positional tracking for workload management, broadcasting the games, and even finding you to deliver a cold beer inside the stadium.

I could go on and on with examples of how science is at the heart of it, but I don’t want to give away all the good stuff. That comes later, in these pages and in your imagination.

This isn’t a textbook or a Football 101. There’s going to be some basic terms and concepts that we simply don’t have time or space to go over here. We think that the kind of person that picks up a book called The Science of Football is going to either already know those basics or be able to look them up and learn as we go along. We hope we’ll neither lose you along the way nor insult your intelligence.

Just a glance at our table of contents tells you that we’ll be covering a lot, breaking things down into a myriad of topics and subtopics. However, you don’t need to read this front to back. Pick and choose according to your interests and your time. Rather than watching talking heads tell you what you just saw, grab this book and read about why it happened in the first place.

Writing a book is a tough task. We can’t write about everything, so don’t expect this to be exhaustive. Similarly, we have to choose where to plant our flag. It’s a moment in time, here in 2022, and things will change. If you’re picking this book up in 2042, you’ll probably laugh at some of the things we thought of as advanced, but I think, like looking back twenty years from now, the game will be both largely the same and nothing alike at all.

I doubt we’ll have twenty-two robots on the field a few decades from now. I think the game will still be men, flawed and fragile but bigger, stronger, and faster, and also smarter. The game’s evolution is part of its draw and this look at the science and technology underlying that evolution is, we hope, going to help the game by making fans smarter as well.

We’re ready, so let’s go to the playbook. In this case, Gus Malzahn’s Auburn playbook from just a few years back. Believe it or not, the playbooks that teams hold so close during seasons often leak out and there are whole sites that have these available!

Huddle up tight with us, team. Second down and seven. Slant right Utah, Indy Back Zip, 52’s the mike, on two. Slant right Utah on two. Ready? Break!

OFFENSE

Casual football fans are naturally drawn to the offensive side of the ball. It’s the unit that usually scores all the touchdowns, produces most of the highlight plays, and generates the league’s biggest superstars.

Since the Associated Press began awarding players the NFL MVP award in 1957, there have been only three years where an offensive player didn’t win. It took exceptional, game-changing performances from Alan Page and Lawrence Taylor on defense to get recognized, and a consistent effort in a strike-shortened season from placekicker Mark Moseley in 1982.

NFL games have typically become high-scoring affairs in the modern era, but that wasn’t always the case.

The earliest offensive innovations, including Knute Rockne’s Notre Dame Box, featured all eleven players bunched tight together near the line of scrimmage. Wide receivers and tight ends weren’t even considered positions at the time.

By 1922, the first season of NFL statistics available on Pro Football Reference, the Canton Bulldogs won the league that year with a 10–0–2 record, averaging only 15.3 points per game.

The modern NFL offense is completely unrecognizable from its early days. Offenses have become more and more spread out, coaches have continued to innovate, players have become more athletic, and rule changes have favored the offense in recent decades.

The average NFL offense in 1922 scored 9.1 points per game. The league hasn’t had teams scoring fewer than 20 points per contest since 1993, with 2020 featuring an all-time high in scoring with 24.8 points per game.

The way the modern NFL offense operates continues to change by the generation, but coaches have always emphasized the importance of blocking, regardless of the era.

Legendary Packers head coach Vince Lombardi stressed blocking when taking over in Green Bay with his implementation of the Packers Sweep. The play was a simple handoff to the running back who tried to run to the outside of the formation to find open space near the sideline. Although the play sounded simple enough, it required constant practice and repetition for his offense to get comfortable with their assignments in order to achieve maximum effectiveness.

The left guard in Lombardi’s power sweep was tasked with the most difficult assignment, pulling all the way across the formation to the other side of the field before having to read who to block based on the defense.

Lombardi turned the Packers Sweep into a science, relying on all eleven players executing as efficiently as possible. The play became a staple of Green Bay’s offense, which went on to win five NFL championships over nine seasons.

Blocking schemes have evolved since the 1960s, but then again, so have the players, including the offensive linemen. As offenses have become more pass-heavy and more up-tempo, it has required offensive linemen to adapt to the times, becoming more athletic and agile. Future Hall of Fame offensive tackle Joe Thomas played in the league as this evolution was taking place.

A four-star recruit out of high school, Thomas stayed in state when he chose who to play for in college, committing to the Wisconsin Badgers. After seeing time as an extra blocker as a true freshman in 2003, Thomas became a full-time starter the next season, starting in every remaining collegiate game despite tearing his ACL as a junior in the Capital One Bowl.

After being named a consensus All-American and receiving the Outland Trophy as the nation’s top interior offensive lineman, Thomas declared for the 2007 NFL Draft. Coming in at over 6’6" and 311 pounds, scouts were enamored with the talented prospect.

The Cleveland Browns selected Thomas with the third overall pick of the 2007 NFL Draft. He spent his entire career with the team from 2007 until retiring in 2017. His accolades include six first-team All-Pro selections, ten Pro Bowl appearances, a place in the Cleveland Browns Ring of Honor, and certainly a future spot in the Pro Football Hall of Fame.

Thomas has stayed close to the game since retiring, working as an analyst for NFL Network and co-hosting The ThomaHawk Show, a podcast with his former teammate Andrew Hawkins.

Having spent a decade and a half around the NFL, Thomas has seen a shift in how teams, scouts, and coaches evaluate offensive linemen in today’s league, and he took some time to share some of that insight with me.

When I first got in the NFL, it was more about big, strong, physical offensive linemen, Thomas told me. Athleticism wasn’t that important because teams were running the ball more and quarterbacks were a lot less mobile.

Tall, imposing quarterbacks like Tom Brady and Ben Roethlisberger required more physical linemen, according to Thomas. When they were standing in the pocket, defenses would need to get through linemen quickly rather than going around them, because these quarterbacks would get the ball out quickly. With a different kind of passing game and fewer designed outside runs, offensive linemen simply needed to be bigger and stronger.

In today’s NFL, that’s no longer the case. Spread offenses, vertical passing attacks, and outside zone schemes are requiring more and more from their linemen, resulting in athleticism becoming a much more important factor.

Penei Sewell is a textbook example of the NFL beginning to value athleticism over size and strength. A standout tackle at Oregon, Sewell was listed at a little over 6’4" heading into the 2021 NFL Draft. Despite his shorter height for a tackle prospect, Sewell showcased some impressive athleticism in the pre-draft process with good scores in the broad jump and 40-yard dash.

Sewell was taken with the seventh overall pick in the 2021 draft and had a strong rookie season, starting 16 of 17 games for the Detroit Lions. Athleticism will help Sewell in his NFL career, but Thomas says it’s not the only thing that makes a valuable offensive lineman in today’s league.

Smarts and consistency play a huge part, Thomas said. As an offensive lineman, your value is the polar opposite of a defensive lineman.

Where defensive linemen and edge defenders are credited for tackles for loss, sacks, fumbles, and turnovers, offensive linemen are measured by their ability to prevent those things. Consistency plays a big factor in that, because even the best performance for a starting left tackle can quickly be derailed by allowing a strip-sack on your quarterback, with a defender causing the QB to fumble before they’re able to get the pass away.

A pancake block is cool, but it doesn’t really impact the play much more than anything else when you’re doing your job correctly, Thomas explained. That’s pretty minor compared to you whiffing your block and giving up a sack. That has a significantly bigger impact on the outcome of the game.

Media outlets and casual fans love to highlight pancake blocks, or blocks where a player is able to drive his defender into the ground, when watching offensive linemen. Pancake blocks were previously one of the few quantifiable ways people could evaluate the position. With the introduction of analytics, and companies like Pro Football Focus, it has changed the way the position is viewed and evaluated.

Unless you played offensive line or were a coach that was heavily involved in the position, it can be hard to understand the value of an offensive lineman, Thomas said. If they don’t know how many times one player did their job correctly compared to another, or have any other way of evaluating linemen, then they’re going to be much more influenced by the pancake blocks and other flashy plays a guy makes.

Teaching fans and media members what goes into playing on the offensive line is important for Thomas, and he feels like the analytics crowd has helped in a big way by highlighting the star linemen like Trent Williams and Zack Martin. While not household names to the average fan, Williams and Martin have begun to receive national recognition and All-Pro selections thanks to sites like Pro Football Focus providing player grades to show how dominant they are at their respective positions.

One of the ways Thomas feels that the evaluations and perceptions of offensive linemen are changing thanks to analytics is conceptualizing every play that they’re involved in. An example that Thomas gives is offensive linemen previously being individually criticized when a defensive end had three or four sacks in a game.

With today’s data, you can contextualize that performance, Thomas said. Instead of the offensive lineman receiving all the blame, you can show if a quarterback was holding onto the ball too long or scrambled out of the pocket, and whether the defender was rushing against a different blocker.

Another big shift in the way offensive linemen are utilized in the NFL has been the versatility of players. In the past, tackles may have never been considered to play elsewhere on the offensive line, and even moving from left tackle to right tackle was considered a big challenge.

That hasn’t been the case in recent years. After being selected in the second round of the 2019 NFL Draft, Green Bay Packers offensive lineman Elgton Jenkins has played all over the offensive line. Since coming into the league, Jenkins has played at least one snap at all five positions on the offensive line, with most of his reps coming at both left guard and left tackle.

I think that coaches are beginning to embrace [offensive line versatility] more, Thomas said. They’re understanding the importance of having your best five linemen on the field. Maybe it’s an analytics thing, but finding guys who can play both guard and tackle can be really helpful heading into a week where you want to find the best five players that match up best with the defense you’re about to be playing.

One of the biggest things that Thomas has noticed from his time as a rookie to now is how much more coaches use advanced concepts to make decisions, including the decision to go for it on fourth down.

The risk-reward paradigm has shifted significantly, and coaches have started to lean into analytics, probability, and statistics. Thomas said. Whether that’s going for two or going for it on fourth down, the decision used to be much more about how coaches would defend the decision to their bosses and fan bases rather than relying on probabilities of success.

One of the big reasons fans didn’t see more aggressive coaches was that they were much more risk-averse, according to Thomas. Whether it was avoiding media criticism or backlash from the fans, old school coaches were much more content with doing things the way they’d always been done.

For a new coach, their job on a day-to-day basis is to avoid getting fired, Thomas said.

Changing Fourth Down

Fourth down used to be synonymous with special teams at all levels of football. It would signify the end of an offensive drive with a punt or field-goal attempt, except in rare circumstances of desperation for teams trying to come back from a large deficit with little time remaining.

The mentality surrounding fourth downs has changed entirely in the NFL. In 2021, the league saw an unprecedented number of fourth-down attempts, with teams going for it 793 times over the course of the regular season. Although the league had an extra week of games, there were 44.05 fourth-down attempts per week in 2021, significantly higher than in 2020, where there were 38.7 fourth-down attempts per week on average.

The evolution of fourth down in the NFL. Graph by the author

What was once viewed as a strategy for Madden video game players has been adopted by head coaches across all levels of football. Although analysis that shows specific game situations, both distance and game time dependent, to go for it on fourth are slowly becoming adopted across the league, perhaps no aspect of the game has been changed more by the adoption of statistical analysis than fourth-down aggressiveness.

Different statistical models have been created, and some adopted by NFL teams to make decisions in regard to going for it on fourth down. The New York Times has its own 4th Down Bot, while NFL’s Next Gen Stats has its own algorithm to determine win probability based on decisions to go for it, punt, or kick a field goal.

There are multiple factors that go into these models that help coaches determine whether to go for it. Field position, distance from the first-down marker, time remaining, and the score all play into the decision from a mathematical perspective, but coaches will also consider matchups and momentum when making their own decisions.

Younger coaches in the NFL have begun to embrace going for it on fourth down, and no one was under more scrutiny for their fourth-down decisions than first-year head coach Brandon Staley in 2021.

Staley was hired to be the head coach for the Los Angeles Chargers after just one season as the Los Angeles Rams defensive coordinator. Although his team led the NFL with 22 fourth-down conversions in 2021, Staley was under heavy fire for the fourth downs that weren’t converted, particularly in the team’s final game of the year.

Needing a win or tie to get into the playoffs, Staley made the bold decision to go for it on fourth down from his own 18-yard line. It was fourth-and-1 with his team trailing by only three points with 9:41 remaining in the third quarter. The Chargers went for it, but running back Austin Ekeler was tackled for a two-yard loss, giving the Las Vegas Raiders the ball back inside the red zone. The Raiders kicked a field goal to go up six points and ultimately won the game in overtime to eliminate Los Angeles from a playoff berth.

I understand the criticism. We felt like we could get the run, Staley said in his postgame press conference. I understand that that decision will be questioned, but in my mindset that’s a yard that we can get.

Despite media outlets hammering Staley’s decision, NFL’s own Next Gen Stats agreed with the decision. Per their model, the Chargers had a 1.4 percent higher chance of winning by going for it rather than punting.

Always Fight, Never Punt

Staley isn’t the first coach to be aggressive on fourth down, and he certainly won’t be the last. There might not be another coach across all levels of football who has drawn more attention to the fourth-down debate than coach Kevin Kelley, former head coach of the high school powerhouse Pulaski Academy known as the coach who never punts.

Kelley started coaching back in 1993, but initially had no plans of ever becoming a coach. After graduating from college with a